Welding rod



Patented July 9, 1929.

UNITED STATES J BIRCHARD GREEN, OF CHICAGO, ILLINOIS.

WELDING ROD.

No Drawing.

This invention relates to the manufacture of steel products,particularly those which -in the course of their production, passthrough the operations of the wire drawing mill. The objects of theinvention are to increase the, efiiciency of such products, to provide amethod whereby articlcsof desired composition and characteristics may beproduced and to insure uniformity of production.

{Theinvention is especially useful in the manufacture of rods and wirefor metallic arc welding purposes and in the production of rivets,stapling and crimping wire and other articles requiring special physicalcharacteristics to best adapt them for the usesin which they areemployed.

Experience has proven that steel produced by the basic open hearthprocess provides the best material for'welding rods, rivets, staplingwire and the like. In practice the molten steel is poured fromthe-furnace into an ingot mould where itcools and solidifies. The ingotis hot rolled into a, billet and the billet then hot rolled into a roundwire rod from one to three-sixteenths inch in diameter and usuallyseveral hundred feet in length. This is coiled and constitutes the rawmaterial of the wire mill.

During the process of hot rolling, the steel is necessarily exposed tothe air, the result being that an iron oxide, generally called scale, isformed on the surface of the rod. This scale is very hard and brittleand must be removed before wire. drawing is possible. In practice thescale is removed by treatment in a bath of hot dilute sulphuric or otheracid, this step being referred to as pickling. After the scale isremoved the rods may be allowed to stand until they have accumulated arust or sull coat, which has value as a lubricant in the wire drawingoperations. An additional lubricant is provided by dipping the rods ina"v tub of hot lime water and then baking. The drawing consists ofsuccessive asses of the rod through'dies which gradual v reduce thediameter and increase the lengthuntil wire of the desired gauge isproduced' Throughout these several operations the steel retains thecharacteristics assumed upon solidification in the ingot mould. Thecrosssectional composition of the ultimate wire is the same as that ofthe original ingot.

In many products of the wire mill, as for during the pickling treatment.

Application filed December 10, 1925. Serial No. 74,629.

instance, in filler rods for welding purposes, the character of thesurface portion of the article is of extreme importance. I

'In fusion welding, one of the common causes of weld failures is thepresence of blow holes in the weld. These blow holes are said to beoften caused by gas present in the tiller rod, the objectionable gasbeing hydrogen. i

In the making of steel, gas may be efiectually removed by variousmethods, as by the addition of a degasifying agent, or by the additionof an agent plus ebullition, or by ebullition alone, the steel whichresults from ,such treatments being known, respectively,

as killed steel, rimmed steel and open steel. However, in the picklingprocess heretofore referred to an additional source of' as isencountered. A chemical reaction t es place in the acid pickling bathduring which free hydrogen is liberated from the acid. It' is well knownthat hydrogen is most active, chemically, at the moment of itsliberation from a compound. In this state it is re ferred to asnascenthydrogen. It is also well known that iron and steel have a strongtendency to absorb hydrogen, especially when the latter is in thenascent state.

' Under ordinary conditions of wire mill operation the steel absorbsvery great quantities of" nascent hydrogen during the pickling operationor, at least, condenses it on the surface of the rod. This absorptiontends to make the rod brittle and to render it unfit for drawing. It hasbeen the practice to remove a portion of this hydrogen, by baking atoven temperature, but it can not be completely so removed, and it ispossible that thatnvhich remains is a contributing cause of inferiorresults from the use of welding rods, particularly from the standpointsof irregular melting and blow holes in the weld.

It appears that the presence of sulphur, beyond a definite proportion,in the surface portion of the coiled steel rod has the effect to induceabsorption of hydrogen during the picklingstep, and to invite attack bythe acid of the pickle solution. It also appears that if the sulphurcontent in the surface portion of the ingot be reduced to -.025 orbelow, the resultant rod will be resistant to the attack of the acid,and will not absorb the free hydrogen liberated by the reactionFurthermore that a welding rod produced from a. steel of this character,other factors being correct, will insure a steady melting rod and, ifproperly applied, will effect an efiicient,

completely fused weld, free from blow holes. Whether or nottheimprovement in the rod is due to the resistance to the attack of the.

acid, or to the non-absorption of hydrogen,

or to some other cause, will not be the subject ofagreement and is notmaterial. I have definitely determined, however, that in respect of wiremill operations a critical value of less than 025% sulphur in thesurface portion of steel exists and that this fact less scrap indrawing, acid brittlenessv is, eliminated and the problem of frequentbreaking during drawing has been overcome.

In making steel with the desired low surface sulphur content I prefer tosegregate the sulphur from the surface toward the -center,rather than toeliminate it altogether.

It is possible to control the casting and cooling of a heat of steel sothat concentra tion of sulphur in the center portion of the ingotwill'reduce the sulphur content in the surface portion below 025%. 'Iobring about this result I have found it desirable to employ the highestpouring temperature that is commercially practicable, to remove gas fromthe molten metal in accordance with the practice which produces rimmedsteel,

and to use the largest size of commercial ingot mould, the latter tohave extremely thick walls, but not so thick as to produce a chilledcasting e'venfat the surface. For example,

I may employ an ingot 20" x 22", having five inch walls and 'pour themolten metal at a temperature of about 2800 F. (1538 C.). I find thatgood results are obtained when the steel has a carbon content from .06to 10%, manganese .30 to .4572), sulphur .035 to 060% and with a Verylow content of other impurities. The ingot may then be rolled intobillets and rods. By the term surface portion as referred to herein, Imean to include the steel in the peripheral portion of ingots, billets,rods and wire to a depth of about 10% of the diameter thereof.

Other means of accomplishing the segregation, or disposition. or removalof sulphur to arrive at a surface content below the critical-value of.025 may occur to those skilled in the art ofsteel making and other usesfor steel of this character may befountl. Alterhative methods,modifications and extensions within the scope of the invention arecontemplated in presenting the following claims.

I claim:

1. A ferrous welding rod having a small sulphur content below 025% inthe surface portion thereof, and higher in the center portion.

2. A ferrous welding rod or wire having a I distributed sulphur contentwhich in the sur-' 'face portion is less than 025% and in the centerportion is more than 025%.

3. A ferrous welding rod or wire containing sulphur throughout the same,the sulphur content being greater in the center portion than in thesurface portion, and being less than 025% in the surface portion.

In testimony whereof I have hereunto subscribed my name. I

J BIRCHARD GREENJ

